Conchapelopia Fittkau

Description

Introduction

Medium-sized larvae, up to 8 mm long. Head pale, posterior margin in general not strongly pigmented; body pale, yellowish-white. Head capsule, longish-oval; cephalic index 0.6. Dorsally S5 anterior to dorso-ventrally aligned DP, S7/S8; pit of S7 much smaller than that of S8, located approximately postero-dorsal to S8; Ventrally S9, S10 and VP form triangle, S9, S10 and SSm aligned obliquely across longitudinal axis; setal sockets increase in size in the following order: S10, S9 and SSm; S9 anterolateral S9 + VP.

Antenna

Almost 1/2 as long as head, 2x as long as mandible. Antennal ratio 3.3-4.9. Basal segment about 10x as long as basal width, with ring organ at 0.6-0.7; segment 2 about 8-10x as long as wide; apical segment about 3/4 as long as segment 3. Style club-shaped distally, extending to middle of last segment. Peg sensilla very small. Blade somewhat shorter or longer than flagellum; basal ring 2.5x as high as wide. Accessory blade slightly shorter than blade.

Mandible

Uniformly curved, strongly narrowed in apical 1/2, almost 3x as long as broad; basal 1/2 strongly broadened. Apical tooth 2x as long as basal width, 1/4 length of mandible; distal 1/2 blackish brown. Inner tooth small, but distinguishable, bluntly-rounded, deeply-recessed; mola insignificantly produced, not protruding beyond inner margin of mandible; seta subdentalis long. Ventrolateral setae located adjacently on outer margin of basal 1/2 of mandible; seta 1 small, obvious peg, 2 simple, 3 divided; distance between setae 2 and 3 2x as great as that between setae 1 and 2; Ring organ situated proximal to seta 3, displaced ventrally.

Maxilla

Basal segment of palp about 4x as long as wide, with ring organ at 0.6-0.7; b seta in 3 sections, middle section 2x as long as other 2 parts.

Body

Without fringe of swim-setae. Anal tubules slender, spindle-shaped, about 5x as long as wide. Subbasal seta of posterior parapod simple. Procercus about 3x as long as wide, with 7 apical setae. Claws of posterior parapod simple; about 15 larger claws with small points on inner and/or outer margin; some smaller claws somewhat darkened.

Notes

Taxonomic Notes

Conchapelopia belongs to the tribe Pentaneurini, and lies within the Thienemannimyia-group of genera. In common with Coffmania, Helopelopia and some Rheopelopia, Conchapelopia has a 3-segmented b sensilla. Rheopelopia is distinguished from Conchapelopia by the lack of any indication of a molar tooth. Conchapelopia and Helopelopia may be differentiated from Coffmania, by the broader pseudoradula (>25% width of M-Appendage vs 10%) and the different granulation. Helopelopia, treated originally as a subgenus of Conchapelopia, may perhaps be best treated as such, given difficulty in differentiating the larva. Indeed study of a wider (near global) range of larvae suggests that the concept of Conchapelopia should be broadened to include at least Helopelopia. However the male hypopygia are distinctive, and reared material of new species from Ohio in the USA suggest the distinctively narrow pseudoradula separates from most Conchopelopia (M. Bolton pers. comm). Vallenduuk and Moller-Pillot (2008) discuss the western European species within the revised concepts of Michiels and Spies (2002). Niitsuma (2008) describes larvae from several Japanese species.

Ecological Notes

The larvae of Conchapelopia range from stenothermic inhabitants of flowing waters and lakes, to warm eurythermic species.

In the southeastern USA, larvae commonly occur on Hester-Dendy multiplate samplers in rivers and streams. The ecology of western Palaearctic species is discussed by Vallenduuk and Moller-Pillot (2008). The genus is diverse in the Holarctic, with 9 species described from the Nearctic and some 14 from the Palaearctic, including 8 from Japan (Niitsuma, 2008). However complications in nomenclature (Michiels and Spies, 2002), synonymy (Niitsuma, 2008) and unconsidered allometric effects of development temperature on species boundaries (Kobayashi and Hayashi, 2001) imply true diversity within the genus remains elusive. Furthermore, various pupal skins not referable to known species indicate that the species list is still incomplete.

From India is described an adult (C. falcistyla), two taxa based on exuviae are reported from South India (Roback and Coffman, 1989) and a larva is recorded from Nepal (Roback and Coffman, 1987). One species is described from Sulawesi, Indonesia. Two species are known from Africa. Immature stages from the Neotropical region also can be ascribed to the genus although none have been described. None are known from Australia.

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